Before you consider a software application for the CMDB, what is the process ? What are you managing via the CMDB ?
Who is managing the information ?
Who is verifying / validation the information
How often is audits taken - monthly / quarterlt
What information is being stored and for what purpose and who wants it

Before you even consider a s/w product, you should have answers to these first

We just implemented an ITSM solution called Changegear and the company I believe is called Sunview Software. CMDB was one component of the suite that we looked at with change management, project management, software license management and help desk being some other areas. We've been really impressed with how easy it was to set up all our assets within the system and it has a really neat graphical dependency type view and many other nifty features. I've used some other CMDB products in the past, but this would be the first that I'd mention. I wish you luck in your search. We searched for over a YEAR and so I know the difficulty with finding something effective.

No question about it John. There is no substitute for having a detailed and hardened process. That is the one area (Config Management) that we could have probably done a better job, but that company really consulted us on the importance of that which was another added benefit with working with them.